Syncyclonema haeggi Dhondt, 1971
DHONDT, A. V. 1971. Systematic revision of Entolium, Propeamussium (Amusiidae) and Syncyclonema (Pectinidae, Bivalvia, Mollusca) of the European Boreal Cretaceous. Bulletin de l’Institut Royal des Sciences Naturelles de Belgique, 47 (32): 1-95, pls. 1-4. [p. 48, pl. 2, pls. 1a-1f]
1827 Pecten laevis Nilsson, 1827
1971 Syncyclonema haggi Dhondt, 1971
1971 Syncyclonema haggi Dhondt, 1971
A. V. Dhondt, 1971, plate 2.
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«Derivatio nominis
For Dr. R. HÄGG who worked. for many years, on Swedish Cretaceous Molluscs and Brachiopods. Location and designation of type~specimens
Palaeontologiska Institutionen, Lund LO 79 t: though recorded in the Original Samling the specimen is at present lost. There are enough topotypes known to make the eventual choice of a neotype unnecessary.
Pecten pusillus ALTH: lost. Stratum typicum:
In cake arenosa et carbonifera (Campanian) (chosen here). Pecten pusillus ALTH: Kreidemergel (Upper-Maastrichtian). Locus typicus :
Kopinge, Sweden (chosen here). Pecten pusillus ALTH: Lemberg (Lwow, U. S. S. R.) (O. D.). Original descriptions
«P. testa suborbiculari convexiuscula, tenui, nitida, laevi; auriculis inaequalibus, minori obtusangula, majori extus rotundata; rostro basali rectangulo, marginibus utrinque rectis.
Diam. 8-10 mm. Descript. ~ Satis tenuis, parum convexa, fere orbicularis, oculo nudo plane laevis & nitida; armato autem tenuissime transversim striata; in speciminibus quibusdam vestigia observantur striarum radiantium punctis minutissimis consistentium. Obs. ~ Ad Pectinem arcuatum proxime accedit; differt vero marginibus rostri rectis, & defectu striarum arcuatum infra auriculas. Locus. ~ In calce arenosa et carbonifera ad Köpinge & ad Svenstorpsmölla vulgaris est species; obvenit etiam in arena viridi ad Köpingemölla; in lapide arenaceo regionis ad Yngsjö & c.» Pecten pusillus
«P. testa laevissima nitida, suborbiculari, compressa, linea cardinis recta, marginibus cardinis rectis, ad medietatem testae decurrentibus, angulo cardinis subrecto, auriculis subaequalibus, altera rectangula, altera obtusa, duobus suJcis linearibus radiantibus circa lineam cardinis ornata. Dim.: Länge 3 Mill. Breite 3½ Mill. Länge des Schlossrandes 2 Mill. Ei-kreisförmig, flach, glatt und glänzend, selbst mit bewaffnetem Auge weder concentrische noch Radialstreifen sichtbar, nur in der Nähe des Stirnrandes eine tiefe Anwachsfurche. Der Schlossrand gerade, die Schlosskanten gerade, bis zur Hälfte der Breite herabreichend, dann ohne einen Winkel zu binden, in den halbkreisförmigen Stirnrand übergehend. Schlosskantenwinkel ein rechter, die Ohren ungleich, das eine rechtwinklig bis zu ⅔ des Schlosskante herabreichend, das zweite an der Schlosslinie stumpfwinklig, dann in einem wenig concaven Bogen längs der Schlosskante bis fast zu ihrem Ende herablaufend. Dieses Ohr zeigt zugleich in der Nähe der Schlosslinie zwei genäherte vertiefte Radiallinien, sonst ist die Oberfläche beider Ohren ganz glatt. Von P. laevis Nils, dem diese Species sehr nahe steht, unterscheidet sie sich durch die noch viel geringere Grösse, den Mangel jeder concentrischen Streifung, die Gestalt der Ohren, und die zwei vertieften Radiallinien des einen Ohres. Sehr selten im Kreidemergel von Lemberg.» Additional description
Number of studied specimens: total: 438
Measurements:
— Vaals: Hervian specimens: n = 59
U. P. D.: 5.2 mm to 10.3 mm, av. 7.1 mm W.: 4.5 mm to 9.3 mm, av. 6.2 mm index H/W = 1.1075 to 1.1818; av. 1.1443 3 specimens 8 specimens 16 specimens 47, 32 — Maastricht: Maastrichtian specimens: n = 62 U. P. D.: 3.2 mm to 10.5 mm; av. 6.2 mm W.: 3.1 mm to 9.1 mm; av. 6.0 mm index H/W = 1.0323 to 1.1538; av. 1.0930 A. A.: 75° to 97°; av. 85° Description of the valves:
Diagnosis. — Small smooth, acline, with semi-circular complete pallial margin, long, straight apical margins and a straight or almost
straight hinge-margin. Apical margins reach ⅔ of the height of the disc. The concentric growth lines are strongly marked on the large anterior auricles. right valve: anterior auricle: deep byssal sinus; large hinge-margin can reach half the total width of the disc. posterior auricle: much smaller than the anterior, completely smooth and obtuse-angled. left valve: anterior auricle: large, with acute or right angle. posterior auricle: as on the right valve. Discussion
Synonymy:
Some of the specimens in the VON HAGENOW collection labelled by that author as Pecten laevis NILSSON are in fact Entolium membranaceum (NILSSON); this explains the use of (pro parte). Whether Pecten pusillus ALTH is really synonymous with S. haggi is difficult to decide without the original ALTH-material. In Dresden I saw specimens from Nagorzany which undoubtedly belong to S. haggi so it is likely that both taxa are synonymous.
Differentiation:
S. haggi differs from all other European Syncyclonema-species by its long apical margins. large auricles and small size.
S. halli (GABB) is similar with S. haggi; on the figures in SPEDEN, 1967 it seems that the American species has smaller auricles than the European one, and some of the figured specimens seem to have shorter apical margins. Generic attribution:
S. haggi (nom. novo for Pecten laevis NILSSON) has a smooth shell a well-developed byssal sinus and is so similar with S. halli that there is little doubt it belongs to Syncyclonema.
Stratigraphical and geographical distribution
Cenomanian: CZECHOSLOVAKIA:
Korycany (Halle, N. M. W.) Turonian: CZECHOSlJOVAKIA:
Briesnitz/Elbe (DR) Kystra (N. M. W.) Lindenau. Böhmisch Zwickau (OR, KO.) Zschernitz (DR) G. D. R.: Plauen (DR) G. F. R.: Hartmannshofer Sandstein. Fürnried (Mü.) Senonian: AUSTRIA:
Gosau. Finstergraben (Mü., N. M. W.) Gosau, Tiefengraben (Geol. Bund. Wien) BELGIUM - THE NETHERLANDS: Geulhem (Ma.) Vaals (I. R. Sc. N. B., Musé.) DENMARK: (Bornholm) : Arnager Fiskerleie (GR) Blykobbe Aa (KO. orig. RAVN 1902, 1946) FRANCE: Dieu-le-Fît (Drôme) (B.) G. D. R.: Plauen (DR.) Strehlen (DR.) G. F. R.: Hoheneggelsen (GH.) Lüneburg (B.) SWEDEN: Köpinge (B., KO., Lund orig. HENNIG. 1897, pI. 2, f. 26) Kullemölla (Lund orig. HÄGG, 1935) Lund (KO.) Östra Sonnarslöv (KO.) Svenstorp (Lund) Sventorpsmölla (KO.) Maastrichtian: BELGIUM ~ THE NETHERLANDS
very common in the Limburg deposits (I. R. Se. N. B., KO.) rare in the Hainaut deposits (I. R Sc. N. B.) DENMARK: Aalborg (KO.) Bjerre Thy (KO.) Eerslev (KO.) Kastrup (KO.) Møens Klint (KO.) Nörholm (KO.) Skovbakken. Aalborg (KO.) Stevns Klint, also many specimens in «Grå kridt» (KO.) Störedal (KO.) Svinklöven. Fjerritslev (KO.) G. D. R.: Rügen (GR coll. VON HAGENOW. orig. WOLANSKY) G. F. R.: Hemmoor (GH.) SWEDEN: Ahus (Lund) U. S. S. R.: Ukraïne : Nagorzany (DR)» ANNIE VALÉRIE DHONDT, 1971
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